Description
Integer overflow in the decode_digit function in puny_decode.c in Libidn2 before 2.0.4 allows remote attackers to cause a denial of service or possibly have unspecified other impact.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libidn | 1.33-2 | — |
| Debian 13 | libidn | 1.33-2 | — |
| Debian 12 | libidn | 1.33-2 | — |
| Debian 9 | libidn2-0 | 0.16-1+deb9u1 | DSA-3988-1 |
| Debian 8 | libidn | 1.29-1+deb8u3 | DLA-1447-1 |
| Debian 8 | libidn2-0 | 0.10-2+deb8u1 | DSA-3988-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 7 | libidn | 1.25-2+deb7u3 | DLA-1084-1 |
| Debian 7 | libidn2-0 | 0.8-2+deb7u1 | DLA-1085-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | libidn | 1.32-3ubuntu1.2 | USN-3434-1 |
| Ubuntu 14.04 LTS | libidn | 1.28-1ubuntu2.2 | USN-3434-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | libidn2-0 | 0.10-3ubuntu0.1~esm1 | USN-3421-2 |
| Ubuntu Pro 14.04 LTS | libidn2-0 | 0.9-1ubuntu0.1~esm1 | USN-3421-2 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | libidn | 1.28-5.3.1 | SUSE-SU-2018:0878-1 |
| SLES 11 SP4 | libidn | 1.10-7.3.1 | SUSE-SU-2018:0903-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | libidn | 1.28-5.3.1 | SUSE-SU-2018:0878-1 |
| SLES for SAP 11 SP4 | libidn | 1.10-7.3.1 | SUSE-SU-2018:0903-1 |
Advisories 8
- USN-3421-2 libidn2-0 vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-3434-1 libidn vulnerability Ubuntu Security Notices (USN) · Apr 22, 2026
- DSA-3988-1 libidn2-0 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1447-1 libidn - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1084-1 libidn - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1085-1 libidn2-0 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2018:0903-1 Security update for libidn SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2018:0878-1 Security update for libidn SUSE / openSUSE Security Updates · May 2, 2025